Caption: K-Ras GTP complex. Computer model showing the structure of a molecule of the K-Ras oncogene protein in complex with GTP (guanosine triphosphate). Ras proteins are involved in transmitting signals within cells. They are GTPase enzymes - they bind and hydrolyze GTP. Mutations in the K-Ras gene is an essential step in the development of many cancers, therefore this protein is classed as an oncogene protein. Ras inhibitors such as benzamidine are being studied as a treatment for cancer.